论文标题
Boss CMASS红移空间星系相关函数中银河组装偏置的证据
Evidence for galaxy assembly bias in BOSS CMASS redshift-space galaxy correlation function
论文作者
论文摘要
构建准确,柔性的Galaxy-Halo连接模型对于在非线性尺度上建模星系聚类至关重要。最近的研究发现,光环浓度本身无法捕获完整的星系组装偏置效应,并且光晕的局部环境可以是星系组装偏置的绝佳指标。在本文中,我们提出了一个扩展的光环职业分布模型(HOD),其中包括基于浓度的组装偏置项和基于环境的组装偏置项。我们使用此模型在2D红移空间2分相关函数(2PCF)上实现了良好的拟合度(CHI^2/dof = 1.35)。我们发现,数据包含两个组装偏差项,并受到数据的强烈青睐,标准的5参数HOD被强烈拒绝。更有趣的是,红移空间2PCF以优先分配星系降低质量光环的方式驱动组装偏置参数。这导致了与观察结果之间的1 sigma一致性范围内的星系 - 果态镜头预测,从而减轻了星系簇和镜头之间的感知张力。我们还展示了对基于环境的积极组装偏置的一致的3-5 sigma偏好,该偏差持续了拟合的变化。我们推测,环境依赖性可能是由合并和反馈等基本过程驱动的,但也可能表明较大的光晕边界,例如Splashback半径。无论如何,这项工作突出了构建灵活的Galaxy-Halo连接模型的重要性,并演示了Redshift Space 2pcf的额外约束功能。
Building accurate and flexible galaxy-halo connection models is crucial in modeling galaxy clustering on non-linear scales. Recent studies have found that halo concentration by itself cannot capture the full galaxy assembly bias effect and that the local environment of the halo can be an excellent indicator of galaxy assembly bias. In this paper, we propose an extended halo occupation distribution model (HOD) that includes both a concentration-based assembly bias term and an environment-based assembly bias term. We use this model to achieve a good fit (chi^2/DoF = 1.35) on the 2D redshift-space 2-point correlation function (2PCF) of the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxy sample. We find that the inclusion of both assembly bias terms is strongly favored by the data and the standard 5-parameter HOD is strongly rejected. More interestingly, the redshift-space 2PCF drives the assembly bias parameters in a way that preferentially assigns galaxies to lower mass halos. This results in galaxy-galaxy lensing predictions that are within 1sigma agreement with the observation, alleviating the perceived tension between galaxy clustering and lensing. We also showcase a consistent 3-5sigma preference for a positive environment-based assembly bias that persists over variations in the fit. We speculate that the environmental dependence might be driven by underlying processes such as mergers and feedback, but might also be indicative of a larger halo boundaries such as the splashback radius. Regardless, this work highlights the importance of building flexible galaxy-halo connection models and demonstrates the extra constraining power of the redshift-space 2PCF.